Other embarrassment could be arranged too -- but the line to harrassment here is narrow...
Also, sometimes the reaction/result of aggressive drivers isn't catastrophic. For instance, today on my way home from work I had 2 different drivers decide to come within a foot of my bike while passing. This is a calculated move, intended to scare me and teach me a lesson. I know because in one case, I asked when we both got to the same red light, and in the other, the rude gestures of the driver. An accelerometer would have shown nothing, as any reaction on my part would probably have been worse than just hoping the driver didn't judge wrong.
It's not just "tight driving" either, other times drivers are rude, make threatening actions with their vehicles or just plain block my motion preventing me from changing lanes, making turns, and so on, which should be captured, but don't cause anything particularly noticeable in accelerometer data.
Alternately, the false positive rate is probably pretty high here too. I have at least 2 places on my daily commute where I short-cut thru alleys and make some pretty jarring curb passages. There is one particularly tricky transition from street to bike path involving 3 turns in a very short distance (30ish feet). On fast days I bet it looks more like reacting to an aggressive driver than most aggressive driver reactions (from an accelerometer point of view).
http://www.vagabondish.com/looxcie-wearable-bluetooth-camera...
And also the GoPro
Neither of which quite match your requirements, though.
http://cgi.ebay.com/808-Car-Keys-Micro-camera-Spy-DVR-Suppor...
and _really_ inexpensive - you get ~60-70 mins of recording on a 4gig card, which is about the internal battery life too. I bough a few of them and am playing with recording my 40min (motorcycle) commute every day...
Again, they miss some of the stated requirements, but at $15 or so they can be forgiven some faults...
two of these accidents were in the heart of cambridge, ma (very bike friendly) on streets with wide bike lanes. one in Arlington (mass ave.)
had i a 360 record of each incident i could prove that each of the drivers was operating as recklessly as a drunkard. i probably would have no-harm-no-fouled the two that profusely apologized and wanted to make sure i was okay. i'm sure they are very careful around bicycles now. the hit-and-run, well, i would have played my role as a litigous american and sued his pants off.
i guess it's time to spec-out a cyclist's black box.
too bad i have to go to work now...
ON MY BIKE!
I guess you could make one in software and have it run on a smartphone in a special mounting bracket somewhere. You could even have it interface with a bluetooth headset/helmet for any audio annotation you want to make (e.g. "that guy in the Mustang is driving really aggressively")
I have had two (thankfully minor) accidents on my Vespa, neither of which were my fault. Having video of the guy making an illegal left turn in front of me could have made the ordeal with the insurance companies less painful. Maybe.